Radiation Sensing Thermoplastic Composite Panels

ABSTRACT

A storage phosphor panel can include an extruded inorganic storage phosphor layer including a thermoplastic polymer and an inorganic storage phosphor material, where the extruded inorganic storage phosphor panel has an image quality comparable to that of a traditional solvent coated inorganic storage phosphor screen. Further disclosed are certain exemplary method and/or apparatus embodiments that can provide inorganic storage phosphor panels including a selected blue dye that can be recycled while maintaining sufficient image quality characteristics.

FIELD OF THE INVENTION

The invention relates generally to the field of inorganic storagephosphor materials. More specifically, the invention relates to meltextrudable and/or injection moldable and/or hot-melt pressablecomposites of inorganic storage phosphor materials and thermoplasticand/or thermoset polymers and methods for making and/or using the same.

BACKGROUND OF THE INVENTION

Near the beginning of the 20^(th) century, it was recognized that amedically useful anatomical image could be obtained when a filmcontaining a radiation-sensitive silver halide emulsion is exposed toX-radiation (X-rays) passing through the patient. Subsequently, it wasrecognized that X-ray exposure could be decreased considerably byplacing a radiographic phosphor panel adjacent to the film.

A radiographic phosphor panel typically contains a layer of an inorganicphosphor that can absorb X-rays and emit light to expose the film. Theinorganic phosphor layer is generally a crystalline material thatresponds to X-rays in an image-wise fashion. Radiographic phosphorpanels can be classified, based on the type of phosphors used, as promptemission panels and image storage panels.

Image storage panels (also commonly referred to as “storage phosphorpanels”) typically contain a storage (“stimulable”) phosphor capable ofabsorbing X-rays and storing its energy until subsequently stimulated toemit light in an image-wise fashion as a function of the stored X-raypattern. A well-known use for storage phosphor panels is in computed ordigital radiography. In these applications, the panel is firstimage-wise exposed to X-rays, which are absorbed by the inorganicphosphor particles, to create a latent image. While the phosphorparticles may fluoresce to some degree, most of the absorbed X-rays arestored therein. At some interval after initial X-ray exposure, thestorage phosphor panel is subjected to longer wave length radiation,such as visible or infrared light (e.g., stimulating light), resultingin the emission of the energy stored in the phosphor particles asstimulated luminescence (e.g., stimulated light) that is detected andconverted into sequential electrical signals which are processed inorder to render a visible image on recording materials, such aslight-sensitive films or digital display devices (e.g., television orcomputer monitors). For example, a storage phosphor panel can beimage-wise exposed to X-rays and subsequently stimulated by a laserhaving a red light or infrared beam, resulting in green or blue lightemission that is detected and converted to electrical signals which areprocessed to render a visible image on a computer monitor. Thestimulating light may also be other sources other than a laser (such asLED lamps), that would permit stimulation of a larger area of thestorage phosphor, and the detection may be done using a two dimensionaldetector, such as a CCD or a CMOS device. Thereafter, images fromstorage phosphor panels can be “erased” by exposure to UV radiation,such as from fluorescent lamps.

Thus, storage phosphor panels are typically expected to store as muchincident X-rays as possible while emitting stored energy in a negligibleamount until after subsequent stimulation; only after being subjected tostimulating light should the stored energy be released. In this way,storage phosphor panels can be repeatedly used to store and transmitradiation images.

However, there exists a need for improved storage phosphor panels. Morespecifically, there exists a need for melt extruded or injection moldedor hot pressed inorganic storage phosphor panel has an image qualitythat is comparable to the image quality of the traditional solventcoated screen of equivalent x-ray absorbance.

SUMMARY OF THE INVENTION

An aspect of this application is to advance the art of medical, dentaland non-destructive imaging systems.

Another aspect of this application is to address in whole or in part, atleast the foregoing and other deficiencies in the related art.

It is another aspect of this application to provide in whole or in part,at least the advantages described herein.

In an aspect, there are provided exemplary melt extruded or injectionmolded or hot pressed inorganic storage phosphor panel embodimentsincluding a melt extruded or injection molded or hot pressed inorganicstorage phosphor layer comprising a thermoplastic polymer and aninorganic storage phosphor material, wherein the melt extruded orinjection molded or hot pressed inorganic storage phosphor panel has animage quality that is comparable to or better than the image quality ofthe traditional solvent coated screen of equivalent x-ray absorbance.

In another aspect, there are also disclosed exemplary inorganic storagephosphor detection system embodiments including a melt extruded orinjection molded or hot pressed inorganic storage phosphor panelcomprising a melt extruded or injection molded or hot pressed inorganicstorage phosphor layer comprising a thermoplastic olefin and aninorganic storage phosphor material.

In a further aspect, there are disclosed exemplary method embodiments ofmaking a melt extruded or injection molded or hot pressed inorganicstorage phosphor panel including providing thermoplastic polymercomprising at least one thermoplastic polymer and an inorganic storagephosphor material; and melt extruding or injection molding or hotpressing the thermoplastic polymer and the inorganic storage phosphormaterial to form a melt extruded or injection molded or hot pressedinorganic storage phosphor layer.

In a further aspect, there is disclosed an exemplary re-cycled inorganicstorage phosphor panel that can include an inorganic storage phosphorlayer including at least one polymer, an inorganic storage phosphormaterial, and a copper phthalocyanine based blue dye.

In a further aspect, there is disclosed an exemplary method forrecycling an inorganic storage phosphor panel that can include providingan inorganic storage phosphor panel comprising at least one polymer, aninorganic storage phosphor material, and a copper phthalocyanine basedblue dye; mechanical grinding the inorganic storage phosphor panel intoa powder or flakes; melt extruding, injection molding or hot pressingthe ground powder or flakes to form a recycled manufactured inorganicstorage phosphor panel.

These objects are given only by way of illustrative example, and suchobjects may be exemplary of one or more embodiments of the invention.Other desirable objectives and advantages inherently achieved by thedisclosed invention may occur or become apparent to those skilled in theart. The invention is defined by the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features, and advantages of theinvention will be apparent from the following more particulardescription of the embodiments of the invention, as illustrated in theaccompanying drawings. The elements of the drawings are not necessarilyto scale relative to each other.

FIGS. 1A-1C depicts exemplary portions of scintillator panels inaccordance with various embodiments of the present disclosure.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following is a description of exemplary embodiments, reference beingmade to the drawings in which the same reference numerals identify thesame elements of structure in each of the several figures.

Exemplary embodiments herein provide storage phosphor panels includingan extruded storage phosphor layer with a thermoplastic polymer and astorage phosphor material, and methods of preparing thereof. It shouldbe noted that while the present description and examples are primarilydirected to radiographic medical imaging of a human or other subject,embodiments of apparatus and methods of the present application can alsobe applied to other radiographic imaging applications. This includesapplications such as non-destructive testing (NDT), for whichradiographic images may be obtained and provided with differentprocessing treatments in order to accentuate different features of theimaged subject.

An important property of the screen is its x-ray absorbance. Dependingon the specific application (orthopedic or mammography or intra-oraldental or extra oral dental or non-destructive testing of metals or . .. ), the energy and the intensity of the radiation that is incident onthe storage phosphor screen will be different. However, in order to bevalue as an x-ray imaging tool, the storage phosphor screen has to havesufficient x-ray absorbance, so as to produce a useful image. Inpractical terms, this requires that ˜40-60% of the extruded storagephosphor screen (by volume) be the storage phosphor material (bariumfluorobromoiodide or cesium bromide).

Another requirement for the storage phosphor screen is that it bereadable from either side of the screen, and in the transmission or thereflection mode, with respect to the direction of incidence of thestimulation radiation used for reading the information in the screen.And it would desirable that the screen can be handled under ambientlighting conditions or room light.

Depending on the specific imaging application (medical radiography ordental radiography or non-destructive testing), the physicalcharacteristics required of the storage phosphor panel can be widelydifferent. However, the divergent physical properties may be defined bya few key properties of the storage phosphor screen, such as its bendingresistance (http://www.taberindustries.com/stiffness-tester), tearresistance(http://jlwinstruments.com/index.php/products/test-solutions/tear-resistance-testing/)or folding resistance(https://www.testingmachines.com/product/31-23-mit-folding-endurance-tester).A summary of various methods to measure these properties is outlined in(http://ipst.gatech.edu/faculty/popil_roman/pdf_presentations/Prediction%20of%20Fold%20Cracking%20Propensity%20through%20Physical%20Testing.pdf). Allthis may be achieved using a single layer or a multi layeredarchitecture, that would include additional, coextruded layers on thescreen, which may contain particulates and/or chemistry to achieve therequired physical properties needed to accommodate the mechanics of thescanner and/or handling by the end user. Further, it is important thatthe extruded storage phosphor screen be recyclable; i.e., it isnecessary that the composition of the screen is such that they canre-used to make the storage phosphor screen, and/or the storage phosphorpart of the screen can be reused to manufacture a new screen.

The stimulation wavelength and the emission wavelength of the storagephosphor panel are generally determined by the specific storagephosphor. The peak stimulation wavelength for the commonly used storagephosphors, the stimulation wavelength is fairly broad, and is in theregion of 550-700 nm. However, the stimulated emission for the europiumdoped barium fluorobromoiodide storage phosphor has peak around 390 nm.

FIG. 1 depicts a portion of an exemplary storage phosphor panel 100 inaccordance with various embodiments of the present disclosure. As usedherein, “storage phosphor panel” is understood to have its ordinarymeaning in the art unless otherwise specified, and refers to panels orscreens that store the image upon exposure to X-radiation and emit lightwhen stimulated by another (generally visible) radiation. As such,“panels” and “screens” are used interchangeably herein. It should bereadily apparent to one of ordinary skill in the art that the storagephosphor panel 100 depicted in FIGS. 1A-1C represents a generalizedschematic illustration and that other components can be added orexisting components can be removed or modified.

Storage phosphor panels disclosed herein can take any convenient formprovided they meet all of the usual requirements for use in computedradiography. As shown in FIG. 1A, the storage phosphor panel 100 mayinclude a support 110 and a melt extruded or injection molded or hotpressed storage phosphor layer 120 disposed over the support 110. Anyflexible or rigid material suitable for use in storage phosphor panelsand does not interfere with the recyclability of storage phosphor screencan be used as the support 110, such as glass, plastic films, ceramics,polymeric materials, carbon substrates, and the like. In certainembodiments, the support 110 can be made of ceramic, (e.g., Al₂O₃,) ormetallic (e.g., Al) or polymeric (e.g., polypropylene) materials. Alsoas shown in FIG. 1A, in an aspect, the support 110 can be coextrudedwith the storage phosphor layer 120. The support may be transparent,translucent, opaque, or colored (e.g., containing a blue or a blackdye). Alternatively, if desired, a support can be omitted in the storagephosphor panel.

In another aspect, an anticurl layer may be coextruded on either side ofthe support, if a support is used, or on side of the storage phosphorscreen, to manage the dimensional stability of the storage phosphorscreen.

The thickness of the support 110 can vary depending on the materialsused so long as it is capable of supporting itself and layers disposedthereupon. Generally, the support can have a thickness ranging fromabout 50 μm to about 1,000 μm, for example from about 80 μm to about1000 μm, such as from about 80 μm to about 500 μm. The support 110 canhave a smooth or rough surface, depending on the desired application. Inan embodiment, the storage phosphor panel does not comprise a support.

The storage phosphor layer 120 can be disposed over the support 110, ifa support is included. Alternatively, the storage phosphor layer 120 canbe melt extruded or injection molded or hot pressed independently asshown in FIG. 1B, or melt extruded or injection molded or hot pressedtogether with an opaque layer, and anticurl layer, and combinationsthereof, e.g., shown as layer 150, in FIG. 1A and FIG. 1C.

The storage phosphor layer 120 can include a thermoplastic polymer 130and a storage phosphor material 140. The thermoplastic polymer 130 maybe a polyolefin, such as polyethylene, a polypropylene, and combinationsthereof, or a polyurethane, a polyester, a polycarbonate, a silicone, asiloxane, a polyvinyl chloride (PVC), a polyvinylidine chloride (PVdC).In an aspect, the polyethylene can be high density poly low densitypolyethylene (LDPE), medium density polyethylene (MDPE), linear lowdensity polyethylene (LLDPE), very low density polyethylene (VLDPE), andthe like. In a preferred embodiment, the thermoplastic polymer 130 islow density polyethylene (LDPE). The thermoplastic polymer 130 can bepresent in the storage phosphor layer 120 in an amount ranging fromabout 1% to about 50% by volume, for example from about 10% to about 30%by volume, relative to the total volume of the storage phosphor layer120.

As used herein, “storage phosphor particles” and “stimulable phosphorparticles” are used interchangeably and are understood to have theordinary meaning as understood by those skilled in the art unlessotherwise specified. “Storage phosphor particles” or “stimulablephosphor particles” refer to phosphor crystals capable of absorbing andstoring X-rays and emitting electromagnetic radiation (e.g., light) of asecond wavelength when exposed to or stimulated by radiation of stillanother wavelength. Generally, stimulable phosphor particles are turbidpolycrystals having particle diameters of several micrometers to severalhundreds of micrometers; however, fine phosphor particles of submicronto nano sizes have also been synthesized and can be useful. Thus, theoptimum mean particle size for a given application is a reflection ofthe balance between imaging speed and desired image sharpness.

Stimulable phosphor particles can be obtained by doping, for example,rare earth ions as an activator into a parent material such as oxides,nitrides, oxynitrides, sulfides, oxysulfides, silicates, halides, andthe like, and combinations thereof. As used herein, “rare earth” refersto chemical elements having an atomic number of 39 or 57 through 71(also known as “lanthanoids”). Stimulable phosphor particles are capableof absorbing a wide range of electromagnetic radiation. In exemplarypreferred embodiments, stimulable phosphor particles can absorbradiation having a wavelength of from about 0.01 to about 10 nm (e.g.,X-rays) and from about 300 nm to about 1400 nm (e.g., UV, visible, andinfrared light). When stimulated with stimulating light having awavelength in the range of visible and infrared light, stimulablephosphor particles can emit stimulated light at a wavelength of fromabout 300 nm to about 650 nm.

Suitable exemplary stimulable phosphor particles for use herein include,but are not limited to, compounds having Formula (I):

MFX_(1-z)I_(z) uM^(a)X^(a) :yA:eQ:tD  (I)

wherein M is selected from the group consisting of Mg, Ca, Sr, Ba, andcombinations thereof;

X is selected from the group consisting Cl, Br, and combinationsthereof;

M^(a) is selected from the group consisting of Na, K, Rb, Cs, andcombinations thereof;

X^(a) is selected from the group consisting of F, Cl, Br, I, andcombinations thereof;

A is selected from the group consisting of Eu, Ce, Sm, Th, Bi, andcombinations thereof;

Q is selected from the group consisting of BeO, MgO, CaO, SrO, BaO, ZnO,Al₂O₃, La₂O₃, In₂O₃, SiO₂, TiO₂, ZrO₂, GeO₂, Nb₂O₅, Ta₂O₅, ThO₂, andcombinations thereof;

D is selected from the group consisting of V, Cr, Mn, Fe, Co, Ni, andcombinations thereof;

z is from about 0.0001 to about 1;

u is from about 0 to about 1;

y is from about 0.0001 to about 0.1;

e is from 0 to about 1; and

t is from 0 to about 0.01.

The amounts represented by “z”, “u”, “y”, “e”, and “t” are molaramounts. The same designations appearing elsewhere in this disclosurehave the same meanings unless otherwise specified. In Formula (I),preferably, M is Ba; X is Br; M^(a) is selected from the groupconsisting of Na, K, and combinations thereof; X^(a) is selected fromthe group consisting of F, Br, and combinations thereof; A is Eu; Q isselected from the group consisting of SiO₂, Al₂O₃, and combinationsthereof; and t is 0.

Other exemplary stimulable phosphor particles for use herein include,but are not limited to, compounds having Formula (II):

(Ba_(1-a-b-c)Mg_(a)Ca_(b)Sr_(c))FX_(1-z)I_(z) rM^(a)X^(a):yA:eQ:tD  (II)

wherein X, M^(a), X^(a), A, Q, D e, t, z, and y are as defined above forFormula (I); the sum of a, b, and c, is from 0 to about 0.4; and r isfrom about 10⁻⁶ to about 0.1.

In Formula (II), preferably X is Br; M^(a) is selected from the groupconsisting of Na, K, and combinations thereof; X^(a) is selected fromthe group consisting of F, Br, and combinations thereof; A is selectedfrom the group consisting of Eu, Ce, Bi, and combinations thereof; Q isselected from the group consisting of SiO₂, Al₂O₃, and combinationsthereof; and t is 0.

Further exemplary stimulable phosphor particles for use herein include,but are not limited to, compounds having Formula (III):

M¹⁺X_(a)M²⁺X′₂ bM³⁺X″3:cZ  (III)

wherein M is selected from the group consisting of Li, na, K, Cs, Rb,and combinations thereof;

M²⁺ is selected from the group consisting of Be, Mg, Ca, Sr, Ba, Zn, Cd,Cu, Pb, Ni, and combinations thereof;

M³⁺ is selected from the group consisting of Sc, Y, La, Ce, Pr, Nd, Pm,Sm, Eu, Gd, Tb, Dy Ho, Er, Tm Yb, Lum Al, Bi, In, Ga, and combinationsthereof;

Z is selected from the group consisting of Ga¹⁺, Ge²⁺, Sn²⁺, Sb³⁺, As³⁺,and combinations thereof;

X, X′ and X″ can be the same or different and each individuallyrepresents a halogen atom selected from the group consisting of F, Br,Cl, I; and 0≤a≤1; 0≤b≤1; 0<c≤0.2.

Preferred stimulable phosphor particles represented by Formulas (I),(II), or (III) include europium activated barium fluorobromides (e.g.,BaFBr:Eu and BaFBrI:Eu), cerium activated alkaline earth metal halides,cerium activated oxyhalides, divalent europium activated alkaline earthmetal fluorohalides, (e.g., Ba(Sr)FBr:Eu²⁺) divalent europium activatedalkaline earth metal halides, rare earth element activated rare earthoxyhalides, bismuth activated alkaline metal halide phosphors, andcombinations thereof.

An alternative to the Eu doped BaFBrI type storage phosphor is, Eu dopedCsBr storage phosphor. This is generally used in the form a binderlessstorage phosphor screen, where the needle shaped Eu doped CsBr particlesare generated by vapor deposition of the material on a substrate, whichis then sealed water impermeable material. Such needle shaped europiumdoped cesium bromide storage phosphor screen has an emission peak around450 nm.

The thermoplastic polymer and the inorganic storage phosphor materialare melt compounded to form composite thermoplastic particles which arethen melt extruded or injection molded or hot pressed to form theinorganic storage phosphor layer. For example, the compositethermoplastic particles can be prepared by melt compounding thethermoplastic polymer with the inorganic storage phosphor material usinga twin screw compounder. The ratio of thermoplastic polymer to inorganicstorage phosphor material (polymer: inorganic storage phosphor) canrange from about 1:100 to about 1:0.01, by weight or volume, preferablyfrom about 1:1 to about 1:0.1, by weight or volume. The composition mayinclude inorganic, organic and/or polymeric additives to manage imagequality and/or the physical properties of the extruded storage phosphorscreen. Examples of the additives include, a blue dye (e.g., ultramarineblue, copper phthalocyanine, . . . ) for managing image quality,surfactants (e.g., sodium dodecyl sulfate) for managing the colloidalstability of the storage phosphor particles, polymers (e.g., ethylenevinylacetate) for managing the rheology of the composite. During meltcompounding, the thermoplastic polymer and the inorganic storagephosphor material can be compounded and heated through multiple heatingzones. For example, in the case of polyolefins, the temperature of theheating zones can vary from ca. 170° C.-250° C., depending on thespecific composition of the polymer/additive blends that are used, andthe period of time in each zone depends on the polymer used and thetemperature of the heating zone. Generally, the polymer can be heatedfor a time and temperature sufficient to melt the polymer andincorporate the inorganic storage phosphor material without decomposingthe polymer. The period of time in each zone can range from about 1second to about 1 minute. In one exemplary embodiment, measured blue dyeis added first to the polymer before compounding with storage phosphorparticles. Upon exiting the melt compounder, the composite thermoplasticmaterial can enter a water bath to cool and harden into continuousstrands. The strands can be pelletized and dried at about 40° C. Thescrew speed and feed rates for each of the thermoplastic polymer 130 andthe inorganic storage phosphor material 140 can be adjusted as desiredto control the amount of each in the composite thermoplastic material.

Alternatives to melt compounding include the creation of the compositemixture in an appropriate solvent where the polymer is dissolved ordispersed and inorganic storage phosphor particles are dispersed,followed by the evaporation of the solvent and the milling of thepolymer/inorganic storage phosphor composite mixture is pelletized usinggrinders, cryo-grinder, densifiers, agglomerators, or any other suitabledevice.

The inorganic storage phosphor/thermoplastic polymer composite materialcan be melt extruded or injection molded or hot pressed to form theinorganic storage phosphor layer in which the inorganic storage phosphormaterial is intercalated (“loaded”) within the thermoplastic polymer.For example, the inorganic storage phosphor/thermoplastic polymercomposite layer can be formed by melt extruding or injection molding orhot pressing the composite thermoplastic material. Without being limitedby theory, it is believed that forming the inorganic storagephosphor/thermoplastic composite layer by melt extrusion or injectionmolding or hot pressing increases the homogeneity of the inorganicstorage phosphor layer, and eliminates the undesirable “evaporatedspace” generated when the solvent is evaporated in the traditionalsolvent-coated panels. A melt extruded or injection molded or hotpressed inorganic storage phosphor/thermoplastic composite panelaccording to the present disclosure can have comparable image quality,as compared to the traditional solvent coated panels, along withimproved mechanical and environmental robustness.

In the case of the inorganic storage phosphor/thermoplastic polymercomposite layer being melt extruded or injection molded or hot pressedin combination with a support layer, the melt processing parameters(temperature, screw speed and pump speed in the case of melt extrusionand injection molding, and temperature and pressure in the case of hotpressing) can be adjusted to control the thickness for each of theinorganic storage phosphor/thermoplastic polymer composite layer and thesupport layer, individually.

The thickness of the inorganic storage phosphor/thermoplastic compositelayer can range from about 10 μm to about 1000 μm, preferably from about50 μm to about 750 μm, more preferably from about 100 μm to about 500μm.

Optionally, the melt extruded or injection molded or hot pressedinorganic storage phosphor panel can include a protective overcoatdisposed over the inorganic storage phosphor/thermoplastic compositelayer, which provides enhanced mechanical strength and scratch andmoisture resistance, if desired.

In an embodiment, a scintillation detection system can include thedisclosed storage phosphor panel 100 coupled, inserted or mounted to atleast one storage phosphor panel reader/scanner 160. Choice of aparticular storage phosphor reader will depend, in part, on the type ofstorage phosphor panel being fabricated and the intended use of theultimate device used with the disclosed storage phosphor panel.

Image Quality Assessment

The image quality assessments were done as described below. The x-raysource was a Carestream Health CS2200 x-ray generator and the imageswere scanned using a Carestream Health CS7600 intra oral dental scanner,in the super high resolution mode. The screens were subjected to anx-ray exposure of 70 kV, 7 mA, 0.16 sec. The pixel values were obtainedusing a flat field exposure of the storage phosphor screen and theresolution was obtained by imaging a line pair phantom, and visualobservation. Image quality assessments obtained herein provide ameasureable line pairs per mm resolution consistently or across a set orbatch of manufactured panels (e.g., an average resolution). For aconstant x-ray exposure, fixed scanner conditions, the pixel valuerepresents the efficiency of the storage phosphor screen in convertingthe incident x-ray photons to optical photons by photostimulatedluminescence, which is detected by the detector and converted intodigital signals (e.g., code values). As a result, the differences in thepixel code value (cv) represent the differences in the efficiencybetween the storage phosphor screens.

Comparative Example 1 (Solvent Coated Screen—No Blue Dye)

A solvent coated storage phosphor panel was prepared by mixing a BFBI:Euphosphor with a solvent package and a binder. The solvent package isprepared by mixing 78 grams of Methylene chloride, 6 grams of Methanol,and 15 grams of 1,3 Dioxolane. The binder is Permuthane (Stahl, PeabodyMass.), which is diluted to 15% in a solvent package listed above. Theother ingredients are added to the weight percentage as specified. Thefilm stabilizer (tetrabutyl ammonium thiosulfate) is a 20% solution thatis added to help prevent iodide formation in both the liquid and coatedstate.

Component Weight Percentage Permuthane Solution 4.185 Methylene chloride26.037 Methanol 2.013 1,3 Dixolane 4.495 Film Stabilizer 0.357 Phosphor62.457 Total 100.0The overcoat layer consists of a mixture of 82% Ethyl Acetate and 18% ofa copolyester (Vitel 2700B by Bostik Americas). The phosphor solutionwas coated onto a PET base support and dried using heated air sectionsto flash off the solvents, with a resultant phosphor coverage of 41g/ft². The overcoat solutions were coated on top of the phosphor layerand dried using heated air sections to flash off the solvents, with aresultant overcoat coverage of 0.65 g/ft2.

Comparative Example 2 (Solvent Coated Screen—1200 ppm Ultramarine BlueDye)

A solvent coated storage phosphor panel was prepared by mixing a BFBI:Euphosphor with a solvent package and a binder. The solvent package isprepared by mixing 78 grams of Methylene chloride, 6 grams of Methanol,and 15 grams of 1,3 Dioxolane. The binder is Permuthane (Stahl, PeabodyMass.), which is diluted to 15% in a solvent package listed above. Theother ingredients are added to the weight percentage as specified. Thefilm stabilizer (tetrabutyl ammonium thiosulfate) is a 20% solution thatis added to help prevent iodide formation in both the liquid and coatedstate. The blue dye (AquaMarine blue from Nubiola) is added at a levelequivalent to 1200 ppm based on phosphor weight.

Component Percentage Permuthane Solution 4.063 Methylene chloride 27.25Methanol 2.15 1,3 Dixolane 5.25 Dowanol PM 0.35 Film Stabilizer 0.35UltraMarine Blue 0.073 Phosphor 60.526 Total 100.0The overcoat layer consists of a mixture of Ethyl acetate, Acetone,Methyl methacrylate polymer (Elvacite 2051), 1-Propene,1,1,2,3,3,3-hexafluoro-polymer with 1,1-difluoroethene (Superflex2500-20), N,N-Ethylenebis(stearamide) (Superslip 6350), and polymethylmethacrylate matte beads. The ratio of components for the solution islisted below:

Component Percentage Ethyl Acetate 67.875 Acetone 22.625 Superflex2500-20 2.74 Elvacite 2051 6.39 SuperSlip 6350 0.183 polymethylmethacrylate 0.183 matte bead Total 100.0The phosphor solution was coated onto a PET base support and dried usingheated air sections to flash off the solvents, with a resultant phosphorcoverage 41 g/ft². The overcoat solutions were coated on top of thephosphor layer and dried using heated air sections to flash off thesolvents, with a resultant overcoat coverage of nominally 0.65 g/ft2.

Comparative Example 3 (Extruded Screen—No Blue Dye) CompositeThermoplastic Particle Production

Inorganic storage phosphor/thermoplastic composite pellets according tothe present disclosure were prepared comprising 80% wt. bariumflurobromoiodide (BFBrI) and 20% wt low density polyethylene (LDPEEM811A, available from Westlake Longview Corp. of Houston, Tex.). Thedie temperature was set to 220° C. and 10 heating zones within thecompounder were set to the temperatures shown in Table 1 below:

TABLE 1 Zone 1 2 3 4 5 6 7 8 9 10 Temp (° C.) 220 220 220 220 220 220220 220 220 220After exiting the die, the inorganic storage phosphor/thermoplasticcomposite pellets, comprising LDPE loaded with BFBrI, entered a 25° C.water bath to cool and hardened into continuous strands. The strandswere then fed into a pelletizer and dried at 40° C.

Extrusion or Hot Pressing of Inorganic Storage Phosphor Layer

The pelletized composite thermoplastic materials were loaded into asingle screw Davis Standard extruder. Within the extruder, heating zoneswere set to the temperatures shown in Table 2

TABLE 2 Davis Extruder Zone Temp 1 390° F. 2 400° F. 3 430° F. 4 430° F.Gate 430° F. Adapter 430° F. Poly line 430° F. Melt pump 430° F.

The pelletized material (composite thermoplastic) was extruded through asingle die with the die temperature set at 430° F. form an extrudedinorganic storage phosphor panel in the thickness range of 100-200microns.

In some cases, the pellets were heat pressed into a flat sheet byplacing compounded pellets between 2 plates and applying pressure up to15,000 psig. using a Carver Hydraulic Press Model C. The plates wereheated to approximately 220° C. The plates were pressed together for atimeframe between 30 and 60 seconds.

Comparative Example 4 (Extruded Screen—1000 ppm Ultramarine Blue Dye)Composite Thermoplastic Particle Production

A sample was prepared as described in comparative example 3, with thedifference that the formulation included a blue dye (ultramarine blue)at a level of 1000 ppm with respect to the weight of the phosphor.

A 0.5% concentration of 65561-A Ultramarine blue in LDPE EM 811AA wasused to create 1000 ppm blue dye concentration in the final inorganicstorage phosphor/thermoplastic polymer composite. In order to achievethis, the undyed EM811A polymer resin and the dyed (0.5% blue) EM811Amasterbatch were blended and compounded with the BFBrI powder using aLeistritz twin screw compounder. The die temperature was set to 220° C.and 10 heating zones within the compounder were set to the temperaturesshown in Table 3 below:

TABLE 3 Zone 1 2 3 4 5 6 7 8 9 10 Temp (° C.) 220 220 220 220 220 220220 220 220 220

After exiting the die, the composite thermoplastic particles, comprisingof 1000 ppm blue dyed LDPE loaded with BFBrI, entered a 25° C. waterbath to cool and hardened into continuous strands. The strands were thenpelletized in a pelletizer and dried at 40° C.

Extrusion or Hot Pressing of Inorganic Storage Phosphor Layer

The pelletized composite thermoplastic materials were loaded into asingle screw Davis Standard extruder. Within the extruder, heating zoneswere set to the temperatures shown in Table 4

TABLE 4 Davis Standard Extruder Zone Temp 1 390° F. 2 400° F. 3 430° F.4 430° F. Gate 430° F. Adapter 430° F. Poly line 430° F. Melt pump 430°F.

The pelletized material (composite thermoplastic) was extruded through asingle die with the die temperature set at 430° F. to form an extrudedinorganic storage phosphor panel in the thickness range of 100-200microns.

In some cases, the pellets were heat pressed into a flat sheet byplacing compounded pellets between 2 plates and applying pressure up to15,000 psig, using a Carver Hydraulic Press Model C. The plates wereeach heated to approximately 220° C. The plates were pressed togetherfor a timeframe between 30 and 60 seconds.

Inventive Example 1 (Hot Pressed Screen—100 ppm Copper PhthalocyanineBlue Dye) Composite Thermoplastic Particle Production

A sample was prepared as described in comparative example 3, with thedifference that the formulation included a blue dye (copperphthalocyanine) at a level of 100 ppm with respect to the weight of thephosphor.

The inventors understand that hundreds of potential blue dye materialsexist that can be used with stimulable storage phosphor panels. However,the inventors have determined that only specific selected blue dyesimprove resolution with exemplary inventive method and/or apparatusembodiments according to the application. For example, the inventorsdetermined copper phthalocyanine based blue dye improves resolution forinventive method and/or apparatus embodiments described herein.

A 10% concentration of 65530-A Trans Blue (copper phthalocyanine) inLDPE EM 811AA was diluted step wise to a concentration of 1% with theLDPE EM811A, available from Westlake Longview Corp. of Houston, Tex. Toachieve the 100 ppm blue dye concentration in the final inorganicstorage phosphor/thermoplastic polymer composite, the undyed EM811Apolymer resin and the dyed (1% blue) EM811A masterbatch were blended andcompounded with the BFBrI powder using a Leistritz twin screwcompounder. The die temperature was set to 220° C. and 10 heating zoneswithin the compounder were set to the temperatures shown in Table 5below:

TABLE 5 Zone 1 2 3 4 5 6 7 8 9 10 Temp (° C.) 220 220 220 220 220 220220 220 220 220

After exiting the die, the composite thermoplastic particles, comprisingof 100 ppm blue dyed LDPE loaded with BFBrI, entered a 25° C. water bathto cool and hardened into continuous strands. The strands were thenpelletized in a pelletizer and dried at 40° C.

Extrusion or Hot Pressing of Inorganic Storage Phosphor Layer

The pelletized composite thermoplastic materials were loaded into asingle screw Davis Standard extruder. Within the extruder, heating zoneswere set to the temperatures shown in Table 6.

TABLE 6 Davis Standard Extruder Zone Temp 1 390° F. 2 400° F. 3 430° F.4 430° F. Gate 430° F. Adapter 430° F. Poly line 430° F. Melt pump 430°F.

The pelletized material (composite thermoplastic) was extruded through asingle die with the die temperature set at 430° F. form an extrudedinorganic storage phosphor panel in the thickness range of 100-200microns.

In some cases, the pellets were heat pressed into a flat sheet byplacing compounded pellets between 2 plates and applying pressure up to15,000 psig, using a Carver Hydraulic Press Model C. The plates wereeach heated to approximately 220° C. The plates were pressed togetherfor a timeframe between 30 and 60 seconds.

Inventive Example 2 (Hot Pressed Screen—200 ppm Copper PhthalocyanineBlue Dye) Composite Thermoplastic Particle Production

A sample was prepared as described in inventive example 1, with thedifference that the formulation included a blue dye (copperphthalocyanine) at a level of 200 ppm with respect to the weight of thephosphor.

Extrusion or Hot Pressing of Inorganic Storage Phosphor Layer

The pelletized composite thermoplastic materials were loaded into asingle screw Davis Standard extruder. Within the extruder, heating zoneswere set to the temperatures shown in Table 7.

TABLE 7 Davis Standard Extruder Zone Temp 1 390° F. 2 400° F. 3 430° F.4 430° F. Gate 430° F. Adapter 430° F. Poly line 430° F. Melt pump 430°F.

The pelletized material (composite thermoplastic) was extruded through asingle die with the die temperature set at 430° F. form an extrudedinorganic storage phosphor panel in the thickness range of 100-200microns.

In some cases, the pellets were heat pressed into a flat sheet byplacing compounded pellets between 2 plates and applying pressure up to15,000 psig, using a Carver Hydraulic Press Model C. The plates wereeach heated to approximately 220° C. The plates were pressed togetherfor a timeframe between 30 and 60 seconds.

The inventors have determined that in exemplary method and/or apparatusembodiments according to the application disclosed herein that using acopper phthalocyanine based blue dye at levels above 200 parts permillion began to negatively impact image quality by reducing signallevels (e.g., reducing emission throughput).

The comparative and inventive examples were characterized as describedabove.

ANALYSIS 1 Relative Screen Efficiency (pixel code Resolution values)(LP/mm) Comparative example 1 3568 14 (Solvent coated screen - no bluedye) Comparative example 2 3295 17 (Solvent coated screen - 1200 ppmultramarine blue dye) Comparative example 3 3290 14 (Extruded screen -no blue dye) Comparative example 4 3195 14 (Extruded screen - 1000 ppmultramarine blue dye) Inventive example 1 3162 18 (Hot pressed screen -100 ppm copper phthalocyanine blue dye) Inventive example 2 2956 19 (Hotpressed screen - 200 ppm copper phthalocyanine blue dye)

Exemplary method and/or apparatus embodiments can provide inorganicstorage phosphor panels including an inorganic storage phosphor layerincluding at least one thermoplastic polyolefin, an inorganic storagephosphor material and a blue dye, where the storage phosphor layer has aresolution of >15 lp/mm, where the blue dye is at least 50% reduced inamount from a conventional solvent coated inorganic storage phosphorscreen having similar resolution. In certain exemplary embodiments, theinorganic storage phosphor panel has an image resolution greater than 16lp/mm. greater than 17 lp/mm. greater than 18 lp/mm, greater than 19lp/mm, or greater than 20 lp/mm. In certain exemplary embodiments, theblue dye is at least 60% reduced in amount, at least 70% reduced inamount, at least 80% reduced in amount, or at least 90% reduced inamount from a conventional solvent coated inorganic storage phosphorscreen having similar resolution.

Exemplary method embodiments using an inorganic storage phosphor panelcan include melt extruding, injection molding or hot pressing materialscomprising at least one thermoplastic polyolefin, an inorganic storagephosphor material and a blue dye to form an extruded inorganic storagephosphor layer, where the storage phosphor layer has a resolution of >15lp/mm, where the blue dye is at least 50% reduced in amount from aconventional solvent coated inorganic storage phosphor screen havingsimilar resolution; exposing the extruded inorganic storage phosphorlayer to x-rays to form a latent image; and exposing the latent image inthe extruded inorganic storage phosphor layer to excitation light togenerate a digital image of the latent image.

Certain exemplary method and/or apparatus embodiments can provideinorganic storage phosphor panels including an inorganic storagephosphor layer including at least one thermoplastic polyolefin, aninorganic storage phosphor material and a blue dye, where the storagephosphor layer has a resolution of >19 lp/mm, resolution of >20 lp/mm,or resolution of >21 lp/mm.

In selected exemplary embodiments, the inorganic storage phosphor panelsare formed by melt extruding, injection molding or hot pressing.

Certain exemplary method and/or apparatus embodiments can provideinorganic storage phosphor panels where the relative screen efficiencyloss is less than 15%, less than 25%, less than 40% compared to astorage phosphor panel without blue dye.

Certain exemplary method and/or apparatus embodiments can provide athermoplastic polyolefin storage phosphor screen which has a resolutionof >15 lp/mm, a resolution of >16 lp/mm, a resolution of >17 lp/mm, aresolution of >18 lp/mm, a resolution of >19 lp/mm, a resolution of >20lp/mm.

Certain exemplary method and/or apparatus embodiments can provide athermoplastic storage phosphor screen which has a resolution of >15lp/mm, a resolution of >16 lp/mm, a resolution of >17 lp/mm, aresolution of >18 lp/mm, a resolution of >19 lp/mm, a resolution of >20lp/mm.

Certain exemplary method and/or apparatus embodiments can provide astorage phosphor screen which has a resolution of >15 lp/mm, aresolution of >16 lp/mm, a resolution of >17 lp/mm, a resolution of >18lp/mm, a resolution of >19 lp/mm, a resolution of >20 lp/mm.

In selected exemplary embodiments, the inorganic storage phosphor screenis formed by melt extruding, injection molding or hot pressing.

Certain exemplary method and/or apparatus embodiments can provide aninorganic storage phosphor panel including an inorganic storage phosphorlayer including at least one thermoplastic polyolefin, an inorganicstorage phosphor material and a copper phthalocyanine based blue dye,wherein the inorganic storage phosphor panel has a image resolutiongreater than 15 lp/mm, greater than 16 lp/mm. greater than 17 lp/mm.greater than 18 lp/mm, greater than 19 lp/mm, or greater than 20 lp/mm.In selected exemplary embodiments, the inorganic storage phosphor layeris formed by melt extruding, injection molding or hot pressing.

Certain exemplary method and/or apparatus embodiments can provide aninorganic storage phosphor panel including an inorganic storage phosphorlayer including at least one thermoplastic polyolefin, an inorganicstorage phosphor material and a blue dye between 1×10² and 3×10² ppm,wherein the inorganic storage phosphor panel has a image resolutiongreater than 18 lp/mm. Certain exemplary method and/or apparatusembodiments can provide an inorganic storage phosphor panel including aninorganic storage phosphor layer including at least one thermoplasticpolyolefin, an inorganic storage phosphor material and a copperphthalocyanine based blue dye, wherein the inorganic storage phosphorpanel has a image resolution greater than 15 lp/mm, greater than 16lp/mm. greater than 17 lp/mm. greater than 18 lp/mm, greater than 19lp/mm, or greater than 20 lp/mm. In selected exemplary embodiments, theinorganic storage phosphor panel is formed by melt extruding, injectionmolding or hot pressing.

Certain exemplary method embodiments can using an inorganic storagephosphor panel including melt extruding, injection molding or hotpressing materials comprising at least one thermoplastic polyolefin, aninorganic storage phosphor material and a copper phthalocyanine basedblue dye between 1×10² and 3×10² ppm to form an extruded inorganicstorage phosphor layer; exposing the extruded inorganic storage phosphorlayer to x-rays to form a latent image; and exposing the latent image inthe extruded inorganic storage phosphor layer to excitation light togenerate a digital image of the latent image.

In one exemplary embodiment, a latent x-ray image in the storagephosphor screen is read by scanning. In one exemplary embodiment, alatent image in the storage phosphor screen is read using reflectancescanning in a reflectance mode or transmissive scanning in atransmissive mode.

Image Quality Assessment

The image quality assessments were done as described below. The extrudedplate is adhered to a black PET (Toray Lumirror X30-10 mil) supportusing an optically clear adhesive (3M 8141). This plate is then placedin the Carestream CS2200 x-ray generator, and exposed to an x-rayexposure of 70 kV, 7 mA, 0.16 sec. This exposed plate, kept in subduedambient light, is then scanned in the Carestream Health CS7600 intraoral dental scanner, in the super high resolution mode. The image issaved as a JPEG file and looked at on a computer monitor for defectcount. The plates are all dental size 2 with an area of approximately12.71 cm².

Applicants have found that inorganic storage phosphor particlesdisclosed herein suffer nano-particle effects when reaching sizes below1 micron including increased viscosity, increased surface roughnessincluding holes and recesses on surfaces and/or agglomeration effects.

Comparative Example 5 Composite Thermoplastic Particle Production

Inorganic storage phosphor/thermoplastic composite pellets according tothe present disclosure were prepared comprising of 86% wt.bariumflurobromoiodide (BFBrI) and 14% wt low density polyethylene (LDPEEM811A, available from Westlake Longview Corp. of Houston, Tex.).

The inorganic storage phosphor particles was characterized using theMicrotrac 9200 FRA, to have 95% of the particles to be ≤8.33 microns and50% of the particles to be ≤4.12 microns in diameter.

The formulation included a blue dye (copper phthalocyanine) at a levelof 100 ppm with respect to the weight of the phosphor. A 10%concentration of 65530-A Trans Blue (copper phthalocyanine) in LDPE EM811AA was diluted step wise to a concentration of 1% with the LDPEEM811A, available from Westlake Longview Corp. of Houston, Tex. Toachieve the 100 ppm blue dye concentration in the final inorganicstorage phosphor/thermoplastic polymer composite, the undyed EM811Apolymer resin and the dyed (1% blue) EM811A masterbatch were blended andcompounded with the BFBrI powder using a Leistritz twin screwcompounder.

The die temperature was set to 220° C. and 10 heating zones within thecompounder were set to the temperatures shown in Table 8 below:

TABLE 8 Zone 1 2 3 4 5 6 7 8 9 10 Temp (° C.) 220 220 220 220 220 220220 220 220 220

After exiting the die, the inorganic storage phosphor/thermoplasticcomposite pellets, comprising LDPE loaded with BFBrI, entered a 25° C.water bath to cool and hardened into continuous strands. The strandswere then fed into a pelletizer and dried at 40° C.

Extrusion of Inorganic Storage Phosphor Layer

The pelletized composite thermoplastic materials were loaded into asingle screw Davis Standard extruder. Within the extruder, heating zoneswere set to the temperatures shown in Table 9

TABLE 9 Davis Extruder Zone Temp 1 390° F. 2 400° F. 3 430° F. 4 430° F.Gate 430° F. Adapter 430° F. Poly line 430° F. Melt pump 430° F.

The pelletized material (composite thermoplastic) was extruded through asingle die with the die temperature set at 430° F. form an extrudedinorganic storage phosphor panel in the thickness range of 100-200microns.

Comparative Example 6 Composite Thermoplastic Particle Production

Inorganic storage phosphor/thermoplastic composite pellets according tothe present disclosure were prepared comprising 83% wt.bariumflurobromoiodide (BFBrI) and 17% wt low density polyethylene (LDPEEM811A, available from Westlake Longview Corp. of Houston, Tex.).

The following differences between comparative example 5 and example 6 isthe weight of the phosphor is 86% versus 83%, there is no blue dye, andthe inorganic storage phosphor particles as characterized using theMicrotrac 9200 FRA, to have 95% of the particles to be ≤7.56 microns and50% of the particles to be ≤4.20 microns in diameter.

The die temperature was set to 220° C. and 10 heating zones within thecompounder were set to the temperatures shown in Table 10 below:

TABLE 10 Zone 1 2 3 4 5 6 7 8 9 10 Temp (° C.) 220 220 220 220 220 220220 220 220 220

After exiting the die, the inorganic storage phosphor/thermoplasticcomposite pellets, comprising LDPE loaded with BFBrI, entered a 25° C.water bath to cool and hardened into continuous strands. The strandswere then fed into a pelletizer and dried at 40° C.

Extrusion of Inorganic Storage Phosphor Layer

The pelletized composite thermoplastic materials were loaded into asingle screw Davis Standard extruder. Within the extruder, heating zoneswere set to the temperatures shown in Table 11

TABLE 11 Davis Standard Extruder Zone Temp 1 390° F. 2 400° F. 3 430° F.4 430° F. Gate 430° F. Adapter 430° F. Poly line 430° F. Melt pump 430°F.

The pelletized material (composite thermoplastic) was extruded through asingle die with the die temperature set at 430° F. form an extrudedinorganic storage phosphor panel in the thickness range of 100-200microns.

Inventive Example 3 Composite Thermoplastic Particle Production

A sample was prepared as described in comparative example 5, with thefollowing differences between comparative example 5 and inventiveexample 3 is there is no blue dye, and the inorganic storage phosphorparticles as characterized using the Microtrac 9200 FRA, to have 95% ofthe particles to be ≤6.78 microns and 50% of the particles to be ≤3.81microns in diameter.

The die temperature was set to 220° C. and 10 heating zones within thecompounder were set to the temperatures shown in Table 12 below:

TABLE 12 Zone 1 2 3 4 5 6 7 8 9 10 Temp (° C.) 220 220 220 220 220 220220 220 220 220

After exiting the die, the composite thermoplastic particles, comprisingof LDPE loaded with BFBrI, entered a 25° C. water bath to cool andhardened into continuous strands. The strands were then pelletized in apelletizer and dried at 40° C.

Extrusion of Inorganic Storage Phosphor Layer

The pelletized composite thermoplastic materials were loaded into asingle screw Davis Standard extruder. Within the extruder, heating zoneswere set to the temperatures shown in Table 13

TABLE 13 Davis Standard Extruder Zone Temp 1 390° F. 2 400° F. 3 430° F.4 430° F. Gate 430° F. Adapter 430° F. Poly line 430° F. Melt pump 430°F.

The pelletized material (composite thermoplastic) was extruded through asingle die with the die temperature set at 430° F. form an extrudedinorganic storage phosphor panel in the thickness range of 100-200microns.

Inventive Example 4 Composite Thermoplastic Particle Production

A sample was prepared as described in comparative example 5, with theprimary differences being: the blue dye (copper phthalocyanine) level isapproximately 200 ppm with respect to the weight of the phosphor and theinorganic storage phosphor particles was characterized using theMicrotrac 9200 FRA, to have 95% of the particles to be ≤6.00 microns and50% of the particles to be ≤3.45 microns in diameter.

Extrusion of Inorganic Storage Phosphor Layer

The pelletized composite thermoplastic materials were loaded into asingle screw Davis Standard extruder. Within the extruder, heating zoneswere set to the temperatures shown in Table 14

TABLE 14 Davis Standard Extruder Zone Temp 1 390° F. 2 400° F. 3 430° F.4 430° F. Gate 430° F. Adapter 430° F. Poly line 430° F. Melt pump 430°F.

The pelletized material (composite thermoplastic) was extruded through asingle die with the die temperature set at 430° F. form an extrudedinorganic storage phosphor panel in the thickness range of 100-200microns.

The comparative and inventive examples were characterized for defects asdescribed above.

ANALYSIS 2 # defects per cm² Comparative example 5 ≥30 Comparativeexample 6 ≥30 Inventive example 3 ≤5 Inventive example 4 ≤5

Exemplary method and/or apparatus embodiments can provide free standinginorganic storage phosphor panels that can include an inorganic storagephosphor layer including at least one polymer, an inorganic storagephosphor material, and a blue dye, where the storage phosphor layer hasfewer than 5 defects per square cm. Certain exemplary method embodimentscan provide methods including combining materials including at least onepolymer, an inorganic storage phosphor material and a blue dye to form amanufactured inorganic storage phosphor layer, where the storagephosphor layer has fewer than 5 defects; exposing the manufacturedinorganic storage phosphor layer to x-rays to form a latent image; andexposing the latent image in the manufactured inorganic storage phosphorlayer to excitation light to generate a digital image of the latentimage. In one embodiment, the combining is by melt extruding, injectionmolding or hot pressing. In one embodiment, a latent image in thestorage phosphor screen is read using reflectance scanning in areflectance mode or transmissive scanning in a transmissive mode. Insome embodiments, the polymer is a thermoplastic polyolefin. In someembodiments, the blue dye is a copper phthalocyanine blue dye.

Certain exemplary method embodiments can provide free standing inorganicstorage phosphor panels including an inorganic storage phosphor layerincluding at least one polymer, an inorganic storage phosphor materialthat has 95% of the particles to be ≤6.8 microns in diameter, and a bluedye, where the storage phosphor layer has fewer than 5 defects persquare cm. Certain exemplary method embodiments can provide methodsincluding combining materials including at least one polymer, aninorganic storage phosphor material that has 95% of the particles to be<6.8 microns in diameter and a blue dye to form an extruded inorganicstorage phosphor layer, where the storage phosphor layer has fewer than5 defects; exposing the extruded inorganic storage phosphor layer tox-rays to form a latent image; and exposing the latent image in theextruded inorganic storage phosphor layer to excitation light togenerate a digital image of the latent image. In one embodiment, thecombining is by melt extruding, injection molding or hot pressing. Inone embodiment, a latent image in the storage phosphor screen is readusing reflectance scanning in a reflectance mode or transmissivescanning in a transmissive mode. In some embodiments, the polymer is athermoplastic polyolefin. In some embodiments, the blue dye is a copperphthalocyanine blue dye.

Certain exemplary method embodiments can provide free standing inorganicstorage phosphor panels including an inorganic storage phosphor layerincluding at least one polymer, an inorganic storage phosphor materialthat has 95% of the particles to be <6.8 microns in diameter, and 50% ofthe particles to be <3.8 microns in diameter and a blue dye, where thestorage phosphor layer has fewer than 5 defects per square cm. Certainexemplary method embodiments can provide methods including combiningmaterials including at least one polymer, an inorganic storage phosphormaterial that has 95% of the particles to be <6.8 microns in diameter,and 50% of the particles to be <3.8 microns in diameter and a blue dyeto form an extruded inorganic storage phosphor layer, where the storagephosphor layer has fewer than 5 defects; exposing the extruded inorganicstorage phosphor layer to x-rays to form a latent image; and exposingthe latent image in the extruded inorganic storage phosphor layer toexcitation light to generate a digital image of the latent image. In oneembodiment, the combining is by melt extruding, injection molding or hotpressing. In one embodiment, a latent image in the storage phosphorscreen is read using reflectance scanning in a reflectance mode ortransmissive scanning in a transmissive mode. In some embodiments, thepolymer is a thermoplastic polyolefin. In some embodiments, the blue dyeis a copper phthalocyanine blue dye.

Certain exemplary method embodiments can provide free standing inorganicstorage phosphor panels including an inorganic storage phosphor layerincluding at least one polymer, an inorganic storage phosphor materialthat has 50% of the particles to be <3.8 microns in diameter and a bluedye, where the storage phosphor layer has fewer than 5 defects persquare cm. Certain exemplary method embodiments can provide methodsincluding melt extruding, injection molding or hot pressing materialsincluding at least one polymer, an inorganic storage phosphor materialthat has 50% of the particles to be <3.8 microns in diameter and a bluedye to form an extruded inorganic storage phosphor layer, where thestorage phosphor layer has fewer than 5 defects; exposing the extrudedinorganic storage phosphor layer to x-rays to form a latent image; andexposing the latent image in the extruded inorganic storage phosphorlayer to excitation light to generate a digital image of the latentimage. In one embodiment, a latent image in the storage phosphor screenis read using reflectance scanning in a reflectance mode or transmissivescanning in a transmissive mode. In some embodiments, the polymer is athermoplastic polyolefin. In some embodiments, the blue dye is a copperphthalocyanine blue dye.

Image Quality Assessment

The image quality assessments were done as described below. The extrudedplate is adhered to a black PET (Toray Lumirror X30-10 mil) supportusing an optically clear adhesive (3M 8141). The solvent coated platesalready had a PET support, and were not subjected to the adhesion of anadditional PET support. This plate is then placed in the CarestreamHealth CS2200 x-ray generator and exposed to an x-ray exposure of 70 kV,7 mA, and 0.16 sec. This exposed plate, kept in subdued ambient light,is then scanned in the Carestream Health CS7600 intra oral-dentalscanner, in the super high resolution mode. The flat field image issaved as a linearized dicom file. The average linearized pixel value andthe standard deviation is calculated using a dicom viewer, and thecoefficient of variation (COV) is calculated as the ratio of thestandard deviation to the average linearized pixel value.

The plates are all dental size 2 with an area of approximately 12.71cm².

Comparative Example 7

A CS7600 intra oral computed radiography plate SN ED005947 was used as acomparative example.

Comparative Example 8

A Durr Dental intra oral computed radiography plate CE 0124 was used asa comparative example.

Comparative Example 9

A solvent coated storage phosphor panel was prepared by mixing a BFBI:Euphosphor with a solvent package and a binder. The solvent package isprepared by mixing 78 grams of Methylene chloride, 6 grams of Methanol,and 15 grams of 1,3 Dioxolane. The binder is Permuthane (Stahl, PeabodyMass.), which is diluted to 15% in a solvent package listed above. Theother ingredients are added to the weight percentage as specified. Thefilm stabilizer (tetrabutyl ammonium thiosulfate) is a 20% solution thatis added to help prevent iodide formation in both the liquid and coatedstate. The blue dye (Ultramarine blue from Nubiola) is added at a levelequivalent to 1200 ppm based on phosphor weight.

TABLE 15 Component Percentage Permuthane Solution 4.063 Methylenechloride 27.25 Methanol 2.15 1,3 Dixolane 5.25 Dowanol PM 0.35 FilmStabilizer 0.35 UltraMarine Blue 0.073 Phosphor 60.526 Total 100.0The overcoat layer consists of a mixture of Ethyl acetate, Acetone,Methyl methacrylate polymer (Elvacite 2051), 1-Propene,1,1,2,3,3,3-hexafluoro-polymer with 1,1-difluoroethene (Superflex2500-20), N,N-Ethylenebis(stearamide) (Superslip 6350), and polymethylmethacrylate matte beads. The ratio of components for the solution islisted below:

TABLE 16 Component Percentage Ethyl Acetate 67.875 Acetone 22.625Superflex 2500-20 2.74 Elvacite 2051 6.39 SuperSlip 6350 0.183polymethyl methacrylate 0.183 matte bead Total 100.0The phosphor solution was coated onto a PET base support and dried usingheated air sections to flash off the solvents, with a resultant phosphorcoverage 41 g/ft². The overcoat solutions were coated on top of thephosphor layer and dried using heated air sections to flash off thesolvents, with resultant overcoat coverage of nominally 0.65 g/ft2.

Comparative Example 10 Composite Thermoplastic Particle Production

Inorganic storage phosphor/thermoplastic composite pellets according tothe present disclosure were prepared comprising 86% wt. bariumflurobromoiodide (BFBrI) and 14% wt low density polyethylene (LDPEEM811A, available from Westlake Longview Corp. of Houston, Tex.). Theinorganic storage phosphor particles was characterized using theMicrotrac 9200 FRA, to have 95% of the particles to be <5.97 microns and50% of the particles to be <3.51 microns in diameter.

The formulation involved blending and compounding of the EM811A polymerresin with the BFBrI powder using a Leistritz GL-400 twin screwcompounder. The screw speed was set at 300 RPM. The die temperature wasset to 220° C. and 10 heating zones within the compounder were set tothe temperatures shown in Table 17 below:

TABLE 17 Zone 1 2 3 4 5 6 7 8 9 10 Temp (° C.) 220 220 220 220 220 220220 220 220 220After exiting the die, the inorganic storage phosphor/thermoplasticcomposite pellets, comprising LDPE loaded with BFBrI, entered a 25° C.water bath to cool and hardened into continuous strands. The strandswere then fed into a pelletizer and dried at 40° C.

Extrusion of Inorganic Storage Phosphor Layer

The pelletized composite thermoplastic materials were loaded into asingle screw Killion extruder. Within the extruder, heating zones wereset to the temperatures shown in Table 18.

TABLE 18 Killion Extruder Zone Temp 1 390° F. 2 420° F. 3 430° F. 4 430°F. Gate 430° F. Die 430° F.The pelletized material (composite thermoplastic) was extruded through asingle die with the die temperature set at 430° F. form an extrudedinorganic storage phosphor panel in the thickness range of 100-200microns.

Inventive Example 5 Composite Thermoplastic Particle Production

A sample was prepared as described in comparative example 10, with thedifference that it contained ultramarine blue dye at a level of 1600 ppmwith respect to the phosphor.

Inventive Example 6 Composite Thermoplastic Particle Production

A sample was prepared as described in inventive example 5, with aprimary difference being the blue dye is copper phthalocyanine insteadof ultramarine blue, at a level of approximately 12.5 ppm with respectto the phosphor.

Inventive Example 7 Composite Thermoplastic Particle Production

A sample was prepared as described in inventive example 5, with aprimary difference being the blue dye is copper phthalocyanine insteadof ultramarine blue, at a level of approximately 50 ppm with respect tothe phosphor.

Inventive Example 8 Composite Thermoplastic Particle Production

A sample was prepared as described in inventive example 5, with aprimary difference being the blue dye is copper phthalocyanine insteadof ultramarine blue, at a level of approximately 50 ppm with respect tothe phosphor, and the use of a polymer processing additive (PSA), KynarSuperflex® 2500-20, from Arkema, at a level of 1000 ppm with respect tothe phosphor.

ANALYSIS 3 Relative CV (with respect Noise to Average Std. (coefficientof comparative Sample Speed Dev. variation CV) example 7) ComparativeExample 7 53055 326 0.61% 100% Comparative Example 8 53991 274 0.51% 83%Comparative Example 9 53966 332 0.62% 100% Comparative Example 10 54266336 0.62% 101% Inventive Example 5 56281 231 0.41% 67% Inventive Example6 55918 239 0.43% 70% Inventive Example 7 58903 163 0.28% 45% InventiveExample 8 59460 121 0.20% 33%

In certain exemplary method and/or apparatus embodiments, the copperphthalocyanine blue dye is configured to reduce noise effects.

Exemplary method and/or apparatus embodiments can provide free standinginorganic storage phosphor panels that can include an inorganic storagephosphor layer including at least one polymer, an inorganic storagephosphor material that has 95% of the particles to be ≤6.8 microns indiameter, and a blue dye, and the inorganic storage phosphor layer has acoefficient of variation in the linearized pixel value that is less thanor equal to 0.40.

Exemplary method and/or apparatus embodiments can provide free standinginorganic storage phosphor panels that can include an inorganic storagephosphor layer including at least one polymer or thermoplasticpolyolefin, an inorganic storage phosphor material that has 95% of theparticles to be ≤6.8 microns in diameter, and 50% of the particles to be≤3.8 microns in diameter and a blue dye, and has a coefficient ofvariation in the linearized pixel value that is less than or equal to0.40.

Exemplary method and/or apparatus embodiments can provide free standinginorganic storage phosphor panels that can include an inorganic storagephosphor layer including at least one polymer, an inorganic storagephosphor material, and a blue dye, where the storage phosphor layer hasa coefficient of variation in the linearized pixel value that is lessthan or equal to 0.40. Certain exemplary method embodiments can providemethods including combining materials including at least one polymer, aninorganic storage phosphor material and a blue dye to form amanufactured inorganic storage phosphor layer, which has a coefficientof variation in the linearized pixel value that is less than or equal to0.40; exposing the manufactured inorganic storage phosphor layer tox-rays to form a latent image; and exposing the latent image in themanufactured inorganic storage phosphor layer to excitation light togenerate a digital image of the latent image. Certain exemplary methodembodiments can provide methods including melt extruding, injectionmolding or hot pressing materials comprising at least one thermoplasticpolyolefin, an inorganic storage phosphor material that has 95% of itsparticles to be ≤6.8 microns in diameter, and 50% of the particles to be≤3.8 microns in diameter and a blue dye to form a manufactured inorganicstorage phosphor layer, which has a coefficient of variation in thelinearized pixel value that is less than or equal to 0.40; exposing themanufactured inorganic storage phosphor layer to x-rays to form a latentimage; and exposing the latent image in the manufactured inorganicstorage phosphor layer to excitation light to generate a digital imageof the latent image. In one embodiment, the combining is by meltextruding, injection molding or hot pressing. In one embodiment, alatent image in the storage phosphor screen is read using reflectancescanning in a reflectance mode or transmissive scanning in atransmissive mode. In some embodiments, the polymer is a thermoplasticpolyolefin. In some embodiments, the blue dye is a copper phthalocyanineblue dye. In one embodiment, the manufactured inorganic storage phosphorlayer has a coefficient of variation in the linearized pixel value thatis less than or equal to 70% of that of an equivalent solvent coatedstorage phosphor screen. In one embodiment, the manufactured inorganicstorage phosphor layer has a coefficient of variation in the linearizedpixel value that is less than or equal less than or equal to half thatof an equivalent solvent coated storage phosphor screen. In certainexemplary embodiments, the inorganic storage phosphor material has 95%of its particles to be ≤6.8 microns in diameter. In certain exemplaryembodiments, the inorganic storage phosphor material has 95% of itsparticles to be ≤6.8 microns in diameter and 95% of the particles to be≥1.0 microns in diameter. In certain exemplary embodiments, the extrudedor manufactured inorganic storage phosphor layer has 95% of itsinorganic storage phosphor material particles to be ≤6.8 microns indiameter and 95% of its inorganic storage phosphor material particles tobe ≥1.0 microns in diameter.

Assessment

An important characteristic of the melt extruded or injection molded orhot pressed inorganic storage phosphor panel is that it can be recycledand reused by simply grinding (e.g., mechanically orelectromechanically) the panels using a standard device such as agrinder, cryo-grinder, densifiers, agglomerators, or any other suitabledevice, and pelletizing it during the crushing process, and/orsubsequently by a compounding processes described above, and extrudingit again as a storage phosphor panel. In order to do be able to recyclethe melt extruded or injection molded or hot pressed inorganic storagephosphor panel effectively, it is beneficial or necessary that thestorage phosphor panel can be ground without abrading the grindingequipment. An important measure of the ability to grind the meltextruded or injection molded or hot pressed inorganic storage phosphorpanel panels without abrading the grinding equipment is its fracturestrength of the panel. It is beneficial or necessary that the fracturestrength of the melt extruded or injection molded or hot pressedinorganic storage phosphor panel panels is as small as possible, whilebeing high enough to sustain routine handling during use.

Thus, it is useful to compare grinding or tearing parameters forinventive and conventional inorganic storage phosphor panels. Forpractical purposes, it is useful to compare the peak torque required(e.g., used) to tear inorganic storage phosphor panels, using a standardor conventional method and equipment, such as the SER (SentmanatExtension Rheometer) Universal Testing Platform from XpansionInstruments (http://www.xinst.com/products.htm). One of the modes ofoperation of the instrument is the “high rate fracture testing”, whichis described in the website (http://www.xinst.com/results_fracture.htm).The operational details of the instrument are described inhttp://www.xinst.com/images/SER_2004_Antec.pdf.

The fracture of the films measured by this device is defined by thefollowing equation.

FS=T_(p)/2Rt

Where FS—Fracture strength of the film being measured (Newtons/meter),Tp—the peak torque applied by the instrument (Newtons meter), R—radiusof the drum (meters), and t—thickness of the film (meters)The peak torque (Tp) required for tearing the panel is described thefollowing equation

Tp=FS×2×R×t

The image quality assessments were done as described below. The x-raysource was a Carestream Health CS2200 x-ray generator and the imageswere scanned using a Carestream Health CS7600 intra oral dental scanner,in the super high resolution mode. The screens were subjected to anx-ray exposure of 70 kV, 7 mA, 0.16 sec. The pixel values were obtainedusing a flat field exposure of the storage phosphor screen and theresolution was obtained by imaging a line pair phantom, and visualobservation. Image quality assessments obtained herein provide ameasureable line pairs per mm (LP/mm) resolution consistently or acrossa set or batch of manufactured panels (e.g., an average resolution). Fora constant x-ray exposure, fixed scanner conditions, the linearizedpixel code value (cv) represents the speed of the storage phosphorscreen in converting the incident x-ray photons to optical photons byphotostimulated luminescence, which is detected by the detector andconverted into digital signals.

Comparative Example 11

A solvent coated intraoral computed radiography panels (CS7600) was usedas a comparative example 11. The panel consists of a BaFBrI phosphorcoated on 7 mil PET support, and has a ˜6 micron PVDF/PMMA overcoat, andthe edges are sealed using the same overcoat material. The totalthickness was 325 microns. Solvent coated intraoral computed radiographypanels currently use a PET support. Applicants further were unable totear an isolated 6 mil PET support, which could be used as the supportfor an intraoral computed radiography panel.

Inventive Example 9 Composite Thermoplastic Particle Production

Inorganic storage phosphor/thermoplastic composite pellets according tothe present disclosure were prepared comprising 86% wt. bariumflurobromoiodide (BFBrI) and 14% wt low density polyethylene (LDPEEM811A, available from Westlake Longview Corp. of Houston, Tex.),contained copper phthalocyanine, a blue dye, at a level of approximately200 ppm with respect to the phosphor.

The formulation involved blending and compounding of the EM811A polymerresin with the BFBrI powder using a Leistritz GL-400 twin screwcompounder. The screw speed was set at 300 RPM. The die temperature wasset to 220° C. and 10 heating zones within the compounder were set tothe temperatures shown in Table 19 below:

TABLE 19 Zone 1 2 3 4 5 6 7 8 9 10 Temp (° C.) 220 220 220 220 220 220220 220 220 220After exiting the die, the inorganic storage phosphor/thermoplasticcomposite pellets, comprising LDPE loaded with BFBrI, entered a 25° C.water bath to cool and hardened into continuous strands. The strandswere then fed into a pelletizer and dried at 40° C.

Extrusion of Inorganic Storage Phosphor Layer

The pelletized composite thermoplastic materials were loaded into asingle screw Davis Standard extruder. Within the extruder, heating zoneswere set to the temperatures shown in Table 20.

TABLE 20 Davis Standard Extruder Zone Temp 1 390° F. 2 420° F. 3 430° F.4 430° F. Gate 430° F. Die 430° F.The pelletized material (composite thermoplastic) was extruded through asingle die with the die temperature set at 430° F. form an extrudedinorganic storage phosphor panel in the thickness range of 100-200microns. The total thickness was 150 microns.

Inventive Example 10 Composite Thermoplastic Particle Production

A sample was prepared as described in inventive example 9, with aprimary difference being that the pelletized material (compositethermoplastic) was co-extruded through a two slot die with a carbonblack containing low density polyethylene (LDPE EM811A, available fromWestlake Longview Corp. of Houston, Tex.), with the die temperature setat 430° F., to form a bilayer extruded inorganic storage phosphor panelin the thickness range of 100-200 microns, with a carbon blackcontaining LDPE layer. The blue dye concentration in the phosphor layerwas 100 ppm with respect to the phosphor, and the total thickness was325 microns.

ANALYSIS 4 Peak Phosphor Screen torque Support layer Screen speed(speed/ Screen (Tp) in Thickness Thickness x-ray (linearized x-rayresolution Newton Sample (microns) (microns) absorbance pixel CV)absorbance) (LP/mm) meter Comparative 175 150 0.259 3556 1.37 × 10⁴ 17Could not Example be torn 11 (maximum torque that can applied by theinstrument is 0.2) Inventive none 150 0.203 2989 1.47 × 10⁴ 18 0.048Example 9 Inventive 175 150 0.232 3186 1.37 × 10⁴ 18 0.102 Example 10

Assessment

An important characteristic of the melt extruded or injection molded orhot pressed inorganic storage phosphor panel, is that it has a lowerbarium leaching rate than traditional solvent coated storage phosphorpanels. The barium leaching rate from the panels was examined bysubmerging 0.67 gms of the panel in an extraction fluid, consisting of 1gms of an aqueous solution of dilute nitric acid that was maintained ata pH of 2.8, at 25° C., for 72 hrs, and the concentration of barium ionsin the solution was measured by ICP/MS.

Comparative Example 12

A solvent coated intraoral computed radiography panels (CS7600) was usedas a comparative example 12. The panel consists of a BaFBrI phosphorcoated on 7 mil PET support, and has a ˜6 micron PVDF/PMMA overcoat, andthe edges are sealed using the same overcoat material. The total surfacearea of the two major surfaces of the panel in contact with theextraction fluid was 25.42 cm², while the total surface are of the fouredges (covered by the edge seal) of the panel in contact with theextraction fluid was 0.216 cm².

Comparative Example 13

A solvent coated intra oral computed radiography panels (CS7600) withthe same construction as the one used in comparative example 12 wasused, with the difference that the panel was chopped into three pieces.The total surface area of the two major surfaces of the panel in contactwith the extraction fluid was 25.42 cm², while the total surface are ofthe twelve edges of the panel (some covered by the edge seal and somenot covered by the edge seal) in contact with the extraction fluid was0.402 cm². However, only four of the twelve edges are not covered by theedge seal. Hence, the surface area of the exposed (without edge seal)edges is 0.186 cm².

Inventive Example 11 Composite Thermoplastic Particle Production

Inorganic storage phosphor/thermoplastic composite pellets according tothe present disclosure were prepared comprising 86% wt. bariumflurobromoiodide (BFBrI) and 14% wt low density polyethylene (LDPEEM811A, available from Westlake Longview Corp. of Houston, Tex.),contained copper phthalocyanine, a blue dye, at a level of approximately90 ppm with respect to the phosphor.

The formulation involved blending and compounding of the EM811A polymerresin with the BFBrI powder using a Leistritz GL-400 twin screwcompounder. The screw speed was set at 300 RPM. The die temperature wasset to 220° C. and 10 heating zones within the compounder were set tothe temperatures shown in Table 21 below:

TABLE 21 Zone 1 2 3 4 5 6 7 8 9 10 Temp (° C.) 220 220 220 220 220 220220 220 220 220After exiting the die, the inorganic storage phosphor/thermoplasticcomposite pellets, comprising LDPE loaded with BFBrI, entered a 25° C.water bath to cool and hardened into continuous strands. The strandswere then fed into a pelletizer and dried at 40° C.

Extrusion of Inorganic Storage Phosphor Layer

The pelletized composite thermoplastic materials were loaded into asingle screw Killion extruder. Within the extruder, heating zones wereset to the temperatures shown in Table 22:

TABLE 22 Killion Extruder Zone Temp 1 390° F. 2 420° F. 3 430° F. 4 430°F. Gate 430° F. Die 430° F.The pelletized material (composite thermoplastic) was extruded through asingle die with the die temperature set at 430° F. form an extrudedinorganic storage phosphor panel in the thickness range of 100-200microns. The total surface area of the two major surfaces of the panelin contact with the extraction fluid was 25.42 cm², while the totalsurface are of the four exposed edges of the panel in contact with theextraction fluid was 0.216 cm².

Inventive Example 12

An extruded inorganic storage phosphor panel with the same constructionas the one used in inventive example 11 was used, with the differencethat the panel was chopped into three pieces. The total surface area ofthe two major surfaces of the panel in contact with the extraction fluidwas 25.42 cm², while the total surface are of the twelve exposed edgesof the panel in contact with the extraction fluid was 0.402 cm².

ANALYSIS 5 Rate of barium Concentration of ions leaching Rate of bariumbarium ions in into the ions leaching Concentration the extractionextraction fluid into the of barium ions fluid after 72 hrs without theextraction fluid in the without the contribution per unit extractionfluid contribution from from the major exposed edge after 72 hrs themajor surface surface area Sample (ppm) (ppm) (ppm/hr) (ppm/hr/cm²)Comparative 320 2880 40 215 Example 12 Comparative 3200 Example 13Inventive 2200 1500 21 52 Example 11 Inventive 3700 Example 12

Assessment

An important characteristic of the melt extruded or injection molded orhot pressed inorganic storage phosphor panel is that it can be recycled.Certain embodiments of melt extruded or injection molded or hot pressedinorganic storage phosphor panels according to the application can berecycled and reused by simply grinding or crushing (e.g., reduce/breakinto small pieces) the inorganic storage phosphor panels using astandard device such as a grinder, cryo-grinder, densifiers,agglomerators, electromechanical grinder, mechanical crusher or anyother suitable device, and the ground material can be melt extruded orinjection molded or hot pressed again to form a recycled inorganicstorage phosphor panel. Alternatively, in one recycling embodiment,after grinding or crushing the inorganic storage phosphor panels, theresulting material can be melt compounded to form compositethermoplastic particles, which are then compounded (e.g., melt extrudedor injection molded or hot pressed) to form a recycled inorganic storagephosphor layer/panel. In order to be able to recycle inorganic storagephosphor panels effectively, it is beneficial or necessary that therecycled material/radiographic panels have an imaging performance thatis comparable to that of the panels prior to recycling. Further, to beable to recycle inorganic storage phosphor panels effectively, it isbeneficial or necessary that no individual components (e.g., blue dye,polymer, phosphor) chemically interact and/or degrade during recyclingto form recycled inorganic storage phosphor panels. In addition, to beable to recycle inorganic storage phosphor panels effectively, it isbeneficial or necessary that recycling process embodiments aremechanical and temperature compatible (e.g., does not degrade individualcomponents) when compounding or forming recycled inorganic storagephosphor panels. Also, to be able to recycle inorganic storage phosphorpanels effectively, it is beneficial or necessary that recycling processembodiments do not interfere or degrade subsequent radiographic imagingprocesses.

In some embodiments, a support can be attached to the inorganic storagephosphor layer and recycled, where the support is made of a polymer(e.g., thermoplastic polymer, a thermoplastic polyolefin polymer athermoplastic polyolefin polymer that is a polyethylene) and the copperphthalocyanine based blue dye. In such embodiments, additional inorganicstorage phosphor material can be added as desired during the re-cyclingprocess (compounding and/or extrusion) to account for the added materialbeing recycled from the support.

In one embodiment, a free standing inorganic storage phosphor panel withor without a support can include an inorganic storage phosphor layer ofat least one polymer, an inorganic storage phosphor material, and acopper phthalocyanine based blue dye, that can be recycled one or moretimes by grinding the panel and extrusion (e.g., with optionalcompounding). In another embodiment, inorganic storage phosphor panelswith or without a support can be re-cycled by melting (without grinding)followed by compounding to form a recycled manufactured panel. In yetanother embodiment, an extrusion step forms sheets of inorganic storagephosphor layers that are larger than individual panels and the extrudedsheet is cut (e.g., separated, sliced) into smaller or individual sizedinorganic storage phosphor panels.

Existing storage phosphor panels are hard to recycle because existingstorage phosphor panels are multilayered structures including, forexample, of polyester (PET) support, with a phosphor/elastic polymercomposite layer coating, and another polymer overcoat, and anotherpolymer edge seal around the panel. Accordingly, recycling existingstorage phosphor panels would require careful separation of each one ofthe components, without intermixing, and/or using complex solvents andnew and inventive processes.

Image Quality Assessment

The image quality assessments were done as described below. The x-raysource was a Carestream Health CS2200 x-ray generator and the imageswere scanned using a Carestream Health CS7600 intra oral dental scanner,in the super high resolution mode. The pixel values were obtained usinga flat field exposure of the storage phosphor screen and the resolutionwas obtained by imaging a line pair phantom, and visual observation.Image quality assessments obtained herein provide a measureable linepairs per mm (LP/mm) resolution consistently or across a set or batch ofmanufactured panels (e.g., an average resolution). For a constant x-rayexposure, fixed scanner conditions, the linearized pixel code value (cv)represents the speed of the storage phosphor screen in converting theincident x-ray photons to optical photons by photostimulatedluminescence, which is detected by the detector and converted intodigital signals.

The x-ray generator was set to an exposure level of 70 kV, 7 mA, 0.16sec. with a 3.5 mm Al filter. The x-ray transmittance was measured usinga Raysafe Xi Unfors densitometer (set at the “hi” level), with andwithout the sample, and the absorbance is calculated using Beer's law(Absorbance=log(Transmittance through air/Transmittance through screen).

Comparative Example 14 Composite Thermoplastic Particle Production

Inorganic storage phosphor/thermoplastic composite pellets according tothe present disclosure were prepared comprising 86% wt. bariumflurobromoiodide (BFBrI) and 14% wt low density polyethylene (LDPEEM811A, available from Westlake Longview Corp. of Houston, Tex.),contained copper phthalocyanine, a blue dye, at a level of approximately60 ppm with respect to the phosphor.

The formulation involved blending and compounding of the EM811A polymerresin with the BFBrI powder using a Leistritz GL-400 twin screwcompounder. The screw speed was set at 300 RPM. The die temperature wasset to 220° C. and 10 heating zones within the compounder were set tothe temperatures shown in Table 23 below:

TABLE 23 Zone 1 2 3 4 5 6 7 8 9 10 Temp (° C.) 220 220 220 220 220 220220 220 220 220After exiting the die, the inorganic storage phosphor/thermoplasticcomposite pellets, comprising LDPE loaded with BFBrI, entered a 25° C.water bath to cool and hardened into continuous strands. The strandswere then fed into a pelletizer and dried at 40° C.

Extrusion of Inorganic Storage Phosphor Layer

The pelletized composite thermoplastic materials were loaded into asingle screw Davis Standard extruder. Within the extruder, heating zoneswere set to the temperatures shown in Table 24

TABLE 24 Davis Standard Extruder Zone Temp 1 390° F. 2 420° F. 3 430° F.4 430° F. Gate 430° F. Die 430° F.The pelletized material (composite thermoplastic) was extruded through asingle die with the die temperature set at 430° F. form an extrudedinorganic storage phosphor panel in the thickness range of 100-200microns.

Inventive Example 13

The panels generated from comparative example 14 were ground using afood processor (Hamilton Beach Big Mouth Deluxe 14-Cup FoodProcessor)—put the panels into food processor, run on high speed forabout 4 minutes or until ground into small pieces, and the powderedflakes from the food processor were compounded and extruded accordingthe procedure described in comparative example 14. In inventive example13, a ratio of the speed to the x-ray absorbance of the recycled panelwas within 15% of the panel prior to recycling.

ANALYSIS 6 Screen Screen speed speed normalized Screen X-ray (linearizedto x-ray resolution Sample absorbance pixel CV) absorbance (LP/mm)Comparative 0.251 3339 1.33 × 10⁴ 17 Example 14 Inventive 0.246 31761.29 × 10⁴ 18 Example 13

In this document, the terms “a” or “an” are used, as is common in patentdocuments, to include one or more than one, independent of any otherinstances or usages of “at least one” or “one or more.” In thisdocument, the term “or” is used to refer to a nonexclusive or, such that“A or B” includes “A but not B,” “B but not A,” and “A and B,” unlessotherwise indicated. In this document, the terms “including” and “inwhich” are used as the plain-English equivalents of the respective terms“comprising” and “wherein.” Also, in the following claims, the terms“including” and “comprising” are open-ended, that is, a system, device,article, or process that includes elements in addition to those listedafter such a term in a claim are still deemed to fall within the scopeof that claim.

Certain exemplary method and/or apparatus embodiments according to theapplication can provide improved re-cycled inorganic storage phosphorlayers/panels. Exemplary embodiments according to the application caninclude various features described herein (individually or incombination).

While the invention has been illustrated with respect to one or moreimplementations, alterations and/or modifications can be made to theillustrated examples without departing from the spirit and scope of theappended claims. In addition, while a particular feature of theinvention can have been disclosed with respect to only one of severalimplementations/embodiments, such feature can be combined with one ormore other features of the other implementations/embodiments as can bedesired and advantageous for any given or particular function. The term“at least one of” is used to mean one or more of the listed items can beselected. The term “about” indicates that the value listed can besomewhat altered, as long as the alteration does not result innonconformance of the process or structure to the illustratedembodiment. Finally, “exemplary” indicates the description is used as anexample, rather than implying that it is an ideal. Other embodiments ofthe invention will be apparent to those skilled in the art fromconsideration of the specification and practice of the inventiondisclosed herein. It is intended that the specification and examples beconsidered as exemplary only, with a true scope and spirit of theinvention being indicated by at least the following claims.

1. A re-cycled inorganic storage phosphor panel comprising: an inorganicstorage phosphor layer comprising at least one polymer, an inorganicstorage phosphor material, and a copper phthalocyanine based blue dye.2. The re-cycled inorganic storage phosphor panel of claim 1, where aratio of the speed to the x-ray absorbance of the panel is within 25% ofthe panel prior to recycling.
 3. The re-cycled inorganic storagephosphor panel of claim 1, where a ratio of the speed to the x-rayabsorbance of the panel is within 15% of the panel prior to recycling 4.The re-cycled inorganic storage phosphor panel of claim 1, where a ratioof the speed to the x-ray absorbance of the panel is within 10% of thepanel prior to recycling.
 5. The re-cycled inorganic storage phosphorpanel of claim 1, where the inorganic storage phosphor panel is recycledby mechanical grinding the panel followed by melt extruding, injectionmolding or hot pressing.
 6. The re-cycled inorganic storage phosphorpanel of claim 1, where the inorganic storage phosphor panel is recycledby mechanical grinding the panel, compounding the ground panel intopellets and melt extruding, injection molding or hot pressing thepellets.
 7. The re-cycled inorganic storage phosphor panel of claim 1,further comprising a support attached to the inorganic storage phosphorlayer, the support comprising the at least one polymer and the copperphthalocyanine based blue dye.
 8. The re-cycled recycled inorganicstorage phosphor panel of claim 1, where the inorganic storage phosphorpanel has a image resolution greater than 17 line pairs per millimeter(lp/mm) or a image resolution greater than 18 line pairs per millimeter(lp/mm).
 9. The re-cycled inorganic storage phosphor panel of claim 1,where the at least one polymer is thermoplastic material comprising atleast one thermoplastic polyolefin or at least one thermoplasticpolyethylene.
 10. The re-cycled inorganic storage phosphor panel ofclaim 1, where the copper phthalocyanine based blue dye is between 50and 250 parts per million (ppm), where the inorganic storage phosphorpanel has a image resolution greater than 16 line pairs per millimeter(lp/mm).
 11. The re-cycled inorganic storage phosphor panel of claim 1,where the inorganic storage phosphor panel is free standing.
 12. Amethod for recycling an inorganic storage phosphor panel comprising:providing an inorganic storage phosphor panel comprising at least onepolymer, an inorganic storage phosphor material, and a copperphthalocyanine based blue dye; mechanical grinding the inorganic storagephosphor panel into a powder or flakes; melt extruding, injectionmolding or hot pressing the ground powder or flakes to form a recycledmanufactured inorganic storage phosphor panel.
 13. The method of claim12, further comprising: compounding the ground powder or flakes intopellets; and melt extruding, injection molding or hot pressing thecompounded pellets to form the recycled manufactured inorganic storagephosphor panel.
 14. The method of claim 12, further comprising: exposingthe recycled manufactured inorganic storage phosphor layer to x-rays toform a latent image; and exposing the latent image in the recycledmanufactured inorganic storage phosphor layer to excitation light togenerate a digital image of the latent image, where a ratio of the speedto the x-ray absorbance of the panel is within 10% of the panel prior torecycling.
 15. The method of claim 14, where the latent image is a flatfield image.